[0001] This invention relates to a valve assembly generally used to control a vacuum motor
in response to a vacuum or pressure signal from a monitored source. More specifically,
this invention relates to a vacuum operated control system that utilizes a trapped
vacuum which gradually decays through an orifice or porous plug during the time that
the vacuum output level is greater than the input vacuum level.
[0002] In an automobile, delay valves are utilized to control various functions, such as
vacuum advance, blend-air doors, thermactor air management systems, and other applications.
Delay valves suitable for idle speed control were disclosed and claimed in U.S. patent
applications having Serial No. 155,241 and No. 155,242, both filed on June 2, 1980,
and assigned to the assignee of this invention. These prior art delay valves have
decay curves graphically illustrating that the vacuum level in an output chamber is
decreasing (or increasing in an input chamber) as a function of time, if the chamber
is sealed from further vacuum input at a level equal to or greater than that of the
output chamber. This decay function is often so slow as to inhibit rapid actuation
of a controlled element, such as a carburetor or air injection system of a vehicle.
Therefore, a principal consideration of the present invention is to allow a normal,
smooth vacuum decay from the output chamber and then, at a predetermined vacuum level,
to rapidly balance the input and output vacuum levels in such valves.
[0003] When such a delay valve is mounted in an automobile, the undesirably slow decay of
the vacuum operated delay valve can inhibit successful completion of the controlled
operation. In some instances, such slow decay can create a secondary problem, such
as the production of a resonant frequency effect in the controlled system which degrades
the desired controlled operation and thus may produce mechanical noise or inhibit
emission control.
[0004] A dump delay valve constructed in accordance with this invention has a body defining
an enclosure with communicating ports and an aperture. A separating plate in the enclosure
defines input and output chambers, and a diaphragm operator is located in the output
chamber to define a third chamber, with the input and output chambers adjacent. The
separating plate defines an aperture, an opening for an umbrella valve, and a port,
all of which communicate between the input and output chambers when open. An umbrella
valve is mounted on the separating plate to seal communication through the opening.
The port opening and the aperture in the separating plate allow fluid communication
at a fixed rate therethrough. A mounting plate is affixed to the diaphragm operator,
and the separating plate port is sealed by a seal attached to a stem positioned in
the output chamber, where the stem is affixed to the mounting plate and is operable
by the diaphragm operator. A bias spring with a known bias force is positioned in
the output chamber to bias the stem and seal toward the normally open position above
the port. The valve body defines an input port communicating between a vacuum (pressure
below atmospheric) source and the input chamber, and an output port from the output
chamber, communicable with a vacuum operable device. The third chamber is maintained
at atmospheric pressure through an aperture in the enclosure.
[0005] In accordance with this invention, a vacuum level in the output chamber greater than
the bias force of the spring will actuate the diaphragm, stem and seal to close the
port. Vacuum depression is introduced into the output chamber through the umbrella
valve when the input vacuum is greater than the output vacuum. As the input vacuum
decreases, the umbrella valve remains sealed as the input and output chambers communicate
through the separating plate aperture or orifice to attain equilibrium. The rate of
equilibrium attainment as a function of time is referred to as a decay function. As
this decay function can be relatively slow it is desirable, in some cases, to provide
a preset condition where immediate communication, and thus immediate vacuum level
equilibrium, is provided between input and output chambers through the separating
plate port. That point along the decay function where this immediate communication
occurs is determined by the bias force of the spring.
[0006] One way of carrying out the invention is described in detail below with reference
to drawings which illustrate only one specific embodiment, in which:-
FIGURE 1 is a schematic illustration of a dump delay valve constructed according to
the invention, and coupled to a vacuum source and a vacuum operated element;
FIGURE 2 is a side view of another embodiment of a dump delay valve;
FIGURE 3 is a cross-section illustration of a porous plug, which may be utilized as
a restrictive flow control orifice in the separating plate aperture and/or port; and
FIGURE 4 is a graphical illustration of delay valve vacuum decay as a function of
time.
[0007] In FIGURE 1 a dump delay valve 10 is shown with a wall structure 12, which, for example,
can be of a hard plastic or formed metal, defining an enclosure 14 in which is mounted
a separating plate 16 generally a portion of wall structure 12. Separating plate 16
in cooperation with the wall structure 12 defines an input chamber 18 and an output
chamber 20. A diaphragm operator 22, generally of a flexible elastomer material such
as rubber or plastic, mounted in output chamber 20 and generally parallel to separating
plate 16, defines a third or atmospheric chamber 24, with output chamber 20 adjacent
to input chamber 18.
[0008] Separating plate 16 defines an umbrella valve opening 26, a port 28 and a fixed orifice
or aperture 30. A porous plug insert 32 may be mounted in orifice 30 to restrict the
fluid flow through this orifice. Porous plug 32 is shown in an enlarged view in FIGURE
3. Such. plugs provide a predetermined flow-rate therethrough, and are utilized to
serve in place of a fixed orifice. These porous plugs are manufactured of a sintered
metal powder compact, such as stainless steel, with a known porosity. Opening 26,
port 28 and fixed orifice 30 all communicate between input chamber 18 and output chamber
20. A raised seal seat 29, which is part of separating plate 16, is formed about port
28. An umbrella valve 34 is mounted on separating plate 16 over umbrella valve opening
26. This umbrella valve seals communication through opening 26 between input chamber
18 and output chamber 20 when a vacuum (i.e., a pressure below atmospheric pressure)
in chamber 20 is greater than or equal to that vacuum in chamber 18. Fixed orifice
30 (or porous plug 32, when inserted in the orifice) communicates between input chamber
18 and output chamber 20 to allow a gradual, controlled rate of change of pressure
or vacuum between chambers 18 and 20. Affixed to the output chamber face 36 of diaphragm
operator 20 is a mounting plate 38 generally a metal element but not limited thereto.
A stem 40 is positioned in output chamber 20 with a seal means 42 of a rubber or flexible
elastomer affixed to one end, and having the opposite end affixed to mounting plate
38. Seal 42 and stem 40 are movable by diaphragm operator 22, so that seal 42 contacts
port 28 to close this port against communication between input chamber 18 and output
chamber 20. A bias spring 44, such as a coiled metal, is positioned in output chamber
20, between separating plate 16 and mounting plate 38, to maintain seal 42 and stem
40 in the open port position as shown in FIGURE 1. Spring 40 can be selected to provide
a bias force of any predetermined value down to 1 or 2 grams-force.
[0009] Wall 12 defines an input port 46 and an output port 48. Ports 46 and 48 are connected
as shown to a vacuum source 50, such as a manifold vacuum line in an automobile engine,
and vacuum operated element 52, such as the vacuum advance of an automobile engine,
over connecting means 54 and 56, respectively. Thus input chamber 18 communicates
with vacuum source 50 through port 46 and connecting means 54. Similarly, output chamber
20 communicates to vacuum-operated element 52 through port 48 and connecting means
56. Wall 12 also defines an aperture 58 between third chamber 24 and a reference pressure
source. As shown, aperture 58 is open to atmosphere, but is capable of communication
to any pressure source to maintain a fixed pressure level in third chamber 24.
[0010] FIGURE 2 illustrates a pressure-operable device of the same type as the vacuum operable
device of FIGURE 1. In FIGURE 2 elements similar to those shown in FIGURE 1 are similarly
numbered. In FIGURE 2 stem 40 is affixed to mounting plate 38 in output chamber 20,
but stem 40 extends through separating port 28 into input chamber 18, wherein seal
42 is mounted on the end thereof to contact seal seat 29 and close port 28 to prevent
communication through port 28 between input chamber 18 and output chamber 20. A second
mounting plate 60 is affixed to diaphragm operator 22, and is positioned in third
chamber 24. In this chamber 24 wall structure 12 defines an end wall 62. Spring 44
is positioned between end wall 62 and mounting plate 60 to bias stem 40 and seal 42
to the normally-open position of port 28.
[0011] In this embodiment connecting means 54 and 56 are connected to a pressure source
64 and a pressure-operable device 66, respectively. Umbrella valve 34 is mounted on
separating plate 16 in output chamber 20. Third chamber 24 is again at a reference
pressure, generally atmospheric pressure.
[0012] The terms "input vacuum" or "input pressure" refer to that vacuum or pressure level
present in input chamber 18, recognizing that it is dependent upon the vacuum source
50 or pressure source 64 for such level. Similarly, "output vacuum" or "output pressure"
refers to that vacuum or pressure level in output chamber 20; the maximum amplitude
of vacuum or pressure level cannot exceed the maximum amplitude of that attained in
the input chamber.
OPERATION
[0013] The dump delay valve 10 is shown in FIGURE 1 in the normally open position, that
is, with port 28 open between input chamber 18 and output chamber 20. Port seal 42
is urged into this open position by bias spring 44, and third chamber 24 is at atmospheric
pressure. When a vacuum is introduced into input chamber 18 from a suitable vacuum
source 50, such as the engine manifold in an automobile, it is communicated to chamber
20 through port 28 and umbrella valve 26. As orifice 30 is open between chambers 18
and 20 there is also communication through this orifice, but at a negligible rate
as compared to flow through port 28 and valve 34. Umbrella valve 34 in FIGURE 1 opens
when the vacuum in input chamber 18 is greater than the vacuum in output chamber 20.
[0014] When the vacuum level in chamber 20 is such that the pressure differential between
chamber 20 and third chamber 24 (which is at atmospheric pressure) is great enough
to overcome the predetermined bias force of spring 44, diaphragm operator 22 actuates
stem 40 and seal 42 to contact seal seat 29 and stop communication through port 28.
If a further vacuum depression exists from vacuum source 50 to input chamber 18 it
will communicate through umbrella valve 34 with opening 26, as well as through orifice
30. When the input and output chambers are at the same vacuum level, umbrella valve
34 seals communication through opening 26 from chamber 18 to chamber 20.
[0015] As the vacuum level in input chamber 18 is reduced, such as from a decrease in manifold
vacuum in an automobile, that is, as the absolute pressure increases toward atmospheric
pressure, there is a fluid flow through orifice 30 to balance the vacuum level between
chambers 18 and 20. This flow through orifice 30 continues as long as (a) the vacuum
level in chamber 20 is greater than that in chamber 18, and (b) the pressure differential
between output chamber 20 and third chamber.24 is great enough to actuate diaphragm
operator 22 to overcome bias spring 44. At that pressure differential between output
chamber 20 and third chamber 24 where diaphragm operator 22 will no longer overcome
the bias force of spring 44, seal 42 and stem 40 are moved to open port 28 for immediate
communication, and therefore equilibrium, between chambers 18 and 20. Port 28 will
be opened at a pressure differential predetermined by the bias force of spring 44.
[0016] The rate of flow or decrease in the vacuum level in output chamber 20 through orifice
30 as a function of time is referred to as the decay of vacuum. This decay function
is graphically illustrated in FIGURE 4 as a curve 70. In FIGURE 4 the abscissa represents
time and the ordinate denotes the vacuum level in output chamber 20 in pressure depression
below atmosphere (vacuum). As shown, the decreasing decay function starts from a point
A representing the largest vacuum in input chamber 18, which is generally where input
chamber 18 vacuum equals output chamber 20 vacuum. From point A to point B curve 70
depicts the decay or decrease of the vacuum in output chamber 20 through orifice 30.
This decrease occurs after separating plate port 28 has been sealed by sealing means
42 and by the accompanying sudden removal or rapid decrease of the vacuum level in
input chamber 18. At point B the pressure differential between output chamber 20 and
third chamber 24 is no longer great enough to actuate diaphragm operator 22 against
the bias force of spring 44, which lifts seal 42 off seat 29. Thus port 28 is open
to communication between chambers 18 and 20 and a vacuum level equilibrium between
these chambers is attained at point C on curve 71, depicting the sharp change of output-chamber
vacuum after seal 42 is moved off port 28. This equilibrium is achieved almost instantaneously
as port 28 is larger, by orders of magnitude, than orifice 30 (or its equivalent when
a porous plug 32 is inserted therein).
[0017] As shown in FIGURE 4 by the extension 72 of the curve 70, if port 28 were maintained
closed, eventually equilibrium between the vacuum levels in chambers 18 and 20 would
be obtained through the continued slow decay through orifice 30. The relative slope
of the decay curve can be altered by a change in the size of orifice 30, or insertion
of an alternative plug 32. The location of point C is dependent upon the bias force
of spring 44, and can be shifted along the curve 70 by changing the spring 44 force.
[0018] The embodiment in FIGURE 2 shows a pressure-operable dump delay valve similar to
that of the vacuum operable valve of FIGURE 1. Valve 10 is shown in a reference or
normally open position and third chamber 24 is at atmospheric pressure. As a fluid
pressure is introduced into input chamber 18 from pressure source 64 through, connecting
means 54 and port 46, it is communicated to output chamber 20 through umbrella valve
opening 26, port 28 and orifice 30. Communication through orifice 30 is very small
as compared to either port 28 or umbrella valve opening 26 when they are open. As
long as the pressure level in input chamber 18 is greater than the pressure in output
chamber 20 umbrella valve 34 remains open. The fluid pressure from pressure source
64 and output chamber 20 is communicated to pressure operable device 66 through output
port 48 and connecting means 56. When the pressure differential between output chamber
20 and third chamber 24 is great enough to actuate diaphragm 22 to overcome the bias
force of spring 44, seal 42 contacts seat 29 to close communication through port 28.
Pressure communication past umbrella valve 34 continues until the pressure in input
chamber 18 equals the pressure in output chamber 20. Should the pressure level in
input chamber 18 decrease after port 28 is sealed, umbrella valve 34 remains closed
and the input chamber 18 and output chamber 20 will seek equilibrium through orifice
30. As the pressure decays through orifice 30, it follows a curve similar in shape
to that of FIGURE 4, until the pressure difference between output chamber 20 and third
chamber 24 is no longer large enough to actuate diaphragm operator 22 against the
bias force of spring 44; this occurs at point C. At that point, stem 40 and seal 42
will be moved to the normally open position, and communication through port 28 will
produce equilibrium between input chamber 18 and output chamber 20.
[0019] This allowance for the rapid balance or equilibrium between the input and output
chambers is a major improvement over present delay valves. As the decay rate proceeds
the vacuum operated device is in a waiting mode, that is, awaiting the vacuum balance
between input and output chambers 18 and 20. During this delay valve lull or neutral
period, no change occurs in the operating device connected to the output port 48,
and in an automobile engine those engine functions dependent upon this vacuum operable
device are also in a holding condition. In at least one specific application of such
a delay valve, the failure to make such a rapid change at a predetermined point causes
an air injection system to attain what can approximately be termed a resonant frequency
effect, which dramatically inhibits its operation, producing mechanical noise and
increasing undesirable exhaust emissions.
1. A dump delay valve (10), comprising:
a wall structure (12) defining an enclosure (14),
a separating plate (16) mounted in said enclosure (14), defining an input chamber
(18) and an output chamber (20), which separating plate (16) defines a port (28),
an aperture (30) and an umbrella valve (26) opening between the input (18) and output
chambers (20) ,
an umbrella valve (34) mounted in said input chamber (18) on the separating plate
(16), to cover said umbrella valve opening (26),
a diaphragm operator (22), mounted in the output chamber (20) defining a third chamber
(24), with the output chamber (20) adjacent the separating plate (16), which diaphragm
operator (22) separates and seals the output (20) and third chambers (24) from each
other,
a mounting plate (38) affixed to the diaphragm operator in said output chamber (20),
said wall structure (12) defining an input port (46) for the input chamber (18), an
output port (48) for the output chamber (20), and an aperture (58) to communicate
said third chamber to atmosphere,
a stem (40) positioned in the output chamber (20), which stem (40) is affixed to said
mounting plate (38) and operable by the diaphragm operator (22),
a seal means (42) affixed near one end of the stem (40) and positioned to abut said
separatinq plate port (28), and
a bias spring (44) with a known bias force, positioned in the output chamber (20)
to bias the diaphragm operator (22) and stem (40) to open the separating plate port
(28) when the pressure difference between the output (20) and third chambers (24)
is less than the bias force of the spring (44).
2. A dump delay valve (10) as claimed in Claim 1, in which the separating plate aperture
(30) is a fixed orifice.
3. A dump delay valve (10) as claimed in Claim 1, and further comprising a porous
plug (32) mounted in the separating plate aperture (30) to thereby allow a restricted
fluid flow between the input (18) and output (20) chambers.
4. A dump delay valve (10) as claimed in Claim 1, wherein the seal means (42) operates
in the output chamber (20) and the umbrella valve (34) in said input (18) chamber
opens to communicate with said output chamber (20).
5. A dump delay valve (10) as claimed in Claim 4, which valve (10) is responsive to
a decreasing vacuum input to open said separating plate port (28) when input vacuum
is less than output vacuum, and the bias spring force is greater than the pressure
differential between the third chamber (24) and the output chamber (20).
6. A dump delay valve (10) as claimed in Claim 4, which valve (10) operates when said
seal means (42) closes communication through said separating plate port (28) to allow
a controlled rate of fluid flow and pressure increase from the input chamber (18)
to the output chamber (20), from a first pressure depression in said output chamber
(20) up to a smaller pressure depression in said input chamber (18), at which pressure
depression said bias spring (44) is operative to bias open said seal means (42)to
thereby instantaneously balance the pressure in said input (18) and output (20) chambers
at a predetermined pressure depression below atmospheric pressure.
7. A dump delay valve (10) as claimed in Claim 1, wherein said seal means (42) is
operable under urging of the bias spring (44) to instantaneously open and communicate
between the input (18) and output (20) chambers, where said bias spring
(44) has a force greater than or equal to the difference between atmospheric pressure
and the pressure level in the output chamber (20).
8. A dump delay valve (10) as claimed in Claim 1, wherein a porous plug (32) is inserted
in the separating plate port (28) to control the rate of change of the difference
between the fluid pressures in the input (18) and output (20) chambers.
9. A dump delay valve (10), comprising:
a wall structure (12) defining an enclosure (14),
a separating plate (16) mounted in said enclosure (14) and defining an input chamber
(18) and an output (20) chamber, which separating plate
(16) defines a port (28), an aperture (30) and an umbrella valve (26) opening between
the input (18) and output (20) chambers,
an umbrella valve (34) mounted in said output (20) chamber on the separating plate
(16), to cover and seal said umbrella valve opening (26),
a diaphragm operator (22) having two flat surfaces, mounted in the output (20) chamber
to define a third (24) chamber, with the output chamber (20) adjacent the separating
plate (16), which diaphragm operator (22) separates and seals the output (20) and
third (24) chambers from each other,
a pair of mounting plates (38,60), one affixed to each flat surface of the diaphragm
operator (22),
said wall structure (12) defining an input port (46) for the input chamber (18), an
output port (48) for the output (20) chamber, and an aperture (58) to communicate
said third chamber (24) to atmosphere,
a stem (40) positioned in the output (20) chamber and affixed to one of said diaphragm
operator (38) mounting plates, and extending through said separating plate port (28)
into said input chamber (18),
a seal means (42) affixed at the end of said stem (40) and positioned to abut said
separating plate port (28),
a bias spring (44) with a known force, positioned in the third chamber (24), and
said wall structure (12) defining an end wall (62), between which end wall (62) and
second mounting plate (60) of the diaphragm operator (22) the bias spring (44) is
positioned to bias said diaphragm operator (22) and stem (40) to open the separating
plate port (28) when the pressure difference between the output chamber (20) and the
third chamber (24), operable on the diaphragm operator (22), is less than the bias
force of said spring (44).
10. A dump delay valve (10) as claimed in Claim 9, wherein the separating plate aperture
(30) is a fixed orifice.
11. A dump delay valve (10) as claimed in Claim 9, and further comprising a porous
plug (32) mounted in the separating plate aperture (30) to thereby allow a restricted
fluid flow between input (18) and output (20) chambers.
12. A dump delay valve (10) as claimed in Claim 9, wherein the seal means (42) is
operative in the input chamber (18) and the umbrella valve (34) in said output chamber
(20) opens to communicate with said input chamber (18).
13. A dump delay valve (10) as claimed in Claim 12, which valve operates to allow
a controlled rate of pressure decrease from a first elevated pressure output level
above atmospheric pressure down to a second elevated pressure above atmospheric pressure
in said output chamber (20), where said bias spring (44) is operative to bias open
said seal means (42) to thereby instantaneously balance the pressure in said input
(18) and output chambers
(20).